Relay



0. S. FIELD July 11, 1939.

RELAY Filed June 29, 1935 FIG. 1.

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1 I r I I I l ,tl t 4 INVENTO a 5. idpz, BY

ATToN E Y Patented July 11, 1939 UNITED STATES PATENT OFFICE eral Railway Signal Company,

Rochester,

Application June 29, 1935, Serial No. 29,121

7 Claims.

This invention relates in general to relays, and more particularly to a relay adapted to respond to direct current impulses.

Certain railway signalling systems employ track circuits which are interrupted at the battery end of one of various rates selected in accordance with traffic conditions to thereby form codes which distinctively afiect decoding apparatus at the relay end for effecting the distant control of wayside signals and the like. A track relay must then be provided which follows these interruptions in the track circuit current in order to condition the decoding means. The type of tractive relay usually employed in continuously energized track circuits is not suitable for this purpose as the comparatively heavy armature required to provide sufiicient back contact pressure has too high inertia to follow the higher frequency code impulses.

It is also important that a relay operating from track circuit current should be as efiicient and sensitive as possible, and consequently the usual track relay is provided with a large amount of iron in its magnetic structure and windings with as large a number of turns as is practical. This arrangement, however, provides an operating winding having rather high self-inductance, which together with the heavy armature prevents the usual track relay from satisfactorily following high frequency coded impulses. It is also important in coded track circuit systems to prevent unauthorized operation of adjacent code following track relays in the event the insulating joint fails to separate adjacent track sections, and consequently the polarity of the impulsed energization of adjacent track sections is transposed or staggered and a means is provided to permit operation of each code following track relay by its particular polarity of energization only.

In view of the above and other considerations, it is proposed in accordance with the present invention to provide an eificient and sensitive relay operable in response to one polarity of en'ergization only and capable of following the frequency of impulses ordinarily employed in coded railway signalling track circuits. More specifically, it is proposed to provide a polarized magnetic structure having an operating winding arranged to control the path of flux in the magnetic structure rather than to create such flux to thereby provide faster contact operation and operation in response to only one polarity of energization. It is further proposed to provide an armature cooperating with such a magnetic structure which has smaller inertia than the heavier armature ordinarily employed in relays to provide sufficient back contact pressure, and to provide reliable contact operation from this low-inertia armature by an improved evacuated inclosure which prevents damage to the contacts from arcing or the like.

Other objects, purposes and characteristic features of the present invention will be obvious as the description thereof progresses, during which references will be made to the accompanying drawing, in which:

Fig. 1 is a side elevational view of a relay constructed in accordance with the present invention and shown as connected to a conventional coded railway signalling track circuit, the relay being shown. partly in section and with certain parts broken away to more clearly show its construction.

Fig. 2 is a sectional side elevational View of a portion of the present relay taken substantially on line 2-2 of Fig. 1.

Fig. 3 is a sectional bottom view of the relay shown in Fig, 1.

In Fig. 1 of the accompanying drawing, the

relay of the present invention is illustrated as applied to a typical coded track circuit. The track circuit is shown diagrammatically as including a source of energy or battery B connected through a coding means C to the right hand end of track rails 4, the track rails 4 being separated from the adjacent track by insulating joints 5 to form the usual track section. The coding means C may be of the usual type employed in train control systems for example, which comprises a plurality of motor driven cam-wheels arranged to operate associated contacts at different frequencies, which contacts are selectively inserted into the track circuit in accordance with trafiic conditions whereby to alternately energize and deenergize the track circuit at Various rates, for example, at rates of '75, 120 or 180 times per minute.

4 The present relay has been provided for the purpose of following or operating its armature in synchronism with these energized and deenergized conditions of the track circuit, whereby to condition suitable decoding apparatus for controlling wayside signals in accordance with forward traffic conditions and for likewise selecting the coding rate for the rear track sections. Such a coded track circuit signalling system is shown, for example, in the prior application of M. Hormats, Ser. No. 15,646, filed April 10, 1935 which became Patent No. 2,122,373 on June 28, 1938.

The operating magnetic structure of the present relay as shown in Fig. 1 comprises two oppositely arranged L-shaped vertical members 6 and l constructed of suitable soft iron magnetic material, these vertical members 6 and 1 being normally magnetized by a bar permanent magnet 8 magnetically coupled to their upper ends. The north and south poles of the permanent magnet 3 have been arbitrarily indicated by the letters. N and S respectively, and the magnet 8 may be retained by a member 9 held to the vertical members 6 and by screws H].

An electro-magnet core extending transversely between the central portions of the members 6 and is provided by two threaded core pieces II and I2 respectively threaded through the central portions of members 6 and l. The threaded core pieces l! and I2 are obviously adjustable to permit an air-gap of various lengths to be provided between their inner ends, and locking nuts l3 are provided on these core pieces II and |2 to retain such an adjusted position. An operating winding W is provided around the core pieces H and i2 between the members 6 and l, the winding W being shown herein as connected across the left hand end of the track rails 4 to thereby be energized by the track circuit impulses generated from battery B by the coding means C.

The armature of the present relay is glass enclosed and is constructed as a unit separate fro-m the magnetic structure just described. The armature unit constructed around two cylindrical pole pieces l6 and H3 is assembled and adjusted before the glass enclosure is placed there-around as will be later described, and during assembly, a suitable jig or clamp will be employed to hold the pole pieces l6 and i8 in their proper parallel relation shown.

The lower ends of the pole pieces I6 and I8 terminate in enlarged square integral pole faces I6 and H3 respectively with non-magnetic cross bars I9 and 20 clampedto the front and rear sides of these pole faces I6 and I8 by bolts 2| as shown in Fig. 2. A vertical spring strip 23 of phosphor-bronze or the like is clamped beneath the nuts of the bolts 2| against each of the pole faces I6 and I8 and these spring strips 23 extend downwardly to movably support a horizontal armature 24 beneath the lower ends of the pole pieces l5 and 8, the lower ends of the spring strips 23 being clamped against the rear edge of the armature 24 by a strip 25 held by screws 26.

An insulating block 28 is attached on the upper side of the armature 24 between the pole faces Hi and I8 by rivets 29, which insulating block 28 carries a movable contact finger 35 attached thereto by rivets 3|, the contact finger 3|] extending forwardly through an enlarged opening in the cross bar 20 and rearwardly through a similar opening in the rear cross bar l9. An upper fixed contact finger 33 and a lower fixed contact finger 34 are arranged respectively above and below the front end of the movable contact finger 39, and both fingers 33 and 34 are provided with low resistance contact points coacting with a low resistance contact point on the movable finger 3i) as shown in Fig. 2. It may be seen in Fig. 1 and Fig. 3 that the upper finger 33 and the lower finger 34 both extend rearwardly in opposite directions with Wider end portions bent at right angles thereto and in opposite directions whereby the upper and lower fingers are attached to a common insulating cross strip 35 by rivets 36. A second insulating cross strip 31 is provided to insulate the ends of the rivets 36 from the metal cross bar 20 and both insulating strips 35 and 31 are clamped in place by the bolts 2|.

An upper stop for the movable contact 35 is provided by a comparatively rigid stop strip 39 having an offset end clamped beneath the head of bolt 2| and extending above the movable finger 30 as shown in Fig. 3 with an insulating button 40 of wood or Bakelite attached to its free end, which button 40 is engaged by a central portion of the movable finger 30 in its upper position. A similar lower stop member 4| is provided having a right angle portion clamped beneath the head of the other bolt 2| and extending beneath the lower fixed contact finger 34 with an insulating button 42 attached to its front end which limits the downward travel of the lower finger 34 and consequently the downward travel of the movable finger 30.

The armature unit after being thus assembled is inserted into a molded glass case 50, a bottom glass disc 5|, although shown in place in the accompanying drawing, is a separate piece which is later attached thus allowing the armature unit to be inserted upwardly into the glass case 5|] so that the pole pieces l6 and I8 extend upwardly through collars molded into the top of the case 50. Metal rings 52 and 54 are molded in these glass collars receiving the pole pieces I6 and 8, which rings are of a suitable metal such as copper which fuses to the surrounding glass to virtually form an integral part of the case 5|]. The protruding upper ends of the rings 52 and 54 are turned or rolled inwardly as shown in Fig. 1 to fit closely around the cores l6 and i8 and when the armature unit is in place within the glass case 50, the lips formed at the ends of the rings 52 and 54 are permanently soldered to the cores l5 and I8 to thereby form a permanent air-tight seal between the glass case 50 and the cores l6 and l8.

A bottom glass disc 5| is now placed against the open bottom of the case 50 and permanently sealed thereto with a suitable frame to form a complete air-tight enclosure. A convenient means for sealing the glass disc 5| to the bottom of the case 50 is to place the complete armature unit assembled within the glass case 50 in a suitable arbor with a means for holding the disc 50 in place and rotate the case 50 with a flame directed at the joint between the case 59 and the disc 5| until the two glass members are fused or sealed together to form an integral air-tight glass enclosure. An evacuating dome 50 is provided at the top of the glass case 53, through which the interior of the glass enclosure may be evacuated and later sealed in the usual manner, either with a suitable degree of vacuum existing therein, or the interior may be filled with an inert gas, all of which is in accordance with the well known practices in connection with evacuated electrical devices.

A lead wire 55 is connected to each of the contact fingers 30, 33 and 34, which lead wires extend through either the sides of the case 50 or the bottom disc 5| and the usual means is employed to fuse the glass to these lead wires to form a permanent air-tight seal. The lead wires 55 are of course connected to suitable terminals for controlling external circuits, and the glass enclosed armature unit is assembled on the operating magnetic structure as shown in Fig. 1 so that the protruding ends of the pole pieces I3 and I8 engage the inwardly turned feet of the L-shape magnetic members 6 and 1 respectively, and a suitable clamping means (not shown) may be provided to retain the armature unit in this position below the operating magnetic structure.

In the complete relay as described and as illustrated in Fig. 1, it will be clear that when the operating winding W is deenergized, the armature 24 is attracted by the flux from the permanent magnet 8 flowing in a counter-clockwise direction, that is, by the flux flowing from the north pole of the permanent magnet downwardly through the vertical member 6, through the pole piece 16, armature 24, pole piece l8 and back to the south pole of the permanent magnet 8 through the vertical member I. This permanent magnet flux attracts the armature 24 toward the pole pieces I6 and I8 and its attracted position is limited by non-magnetic residual pins 44 arranged to enforce a separation between the armature and the pole faces which is found to provide the desired armature releasing characteristics.

The armature 24 in this position obviously engages the movable contact finger 30 with the upper contact finger 33.

When the operating winding W is energized from the track circuit as shown in Fig. 1, current flows from left to right through winding W thereby forming a north electro-magnetic pole at the outer end of core piece 12 and a south electro-magnetic pole at the outer end of core piece II, and the energization of winding W and the air gap separating the core pieces H and I2 are relatively adjusted to provide electro-magnetic poles of intensity substantially equal to that of the permanent magnet poles. It will now be clear that the poles of the permanent magnet 8 tend to produce a flux flowing in a counterclockwise direction through the lower part of the magnetic circuit including armature 24 but the poles produced by energization of winding W tend to send flux in the opposite or clockwise direction through this same part of the magnetic circuit including armature 24 with the result that the flux in this part of the magnetic structure or in armature 24 is reduced tosubstantially zero value and the flux is confined to a local circuit at the upper part of the magnetic structure which circuit includes the electro-magnet in series with the permanent magnet.

In other words, when the winding W is deenergized, the majority of the flux of the permanent magnet does not flow through the electro-magnet core pieces II and I2 because of the high reluctance provided by the air gap separating their inner ends, but rather the most of this permanent magnet flux flows downwardly through the vertical members 6 and I to attract the armature 24. However upon energization of the operating winding W, a local flux 'path is formed through the permanent magnet 8 and the electro-magnet core pieces II and I2 wherein the intensity of the permanent magnet poles is increased by the electro-magnet poles to send the majority of the flux through the air gap separating the inner ends of the core pieces H and I2, but the magnetic potential tending to send flux through the lower portion of the vertical members 6 and 1 is substantially neutralized and consequently the armature 24 is released and the gravitational bias thereon operates contact finger 30 into engagement with the lower contact finger 34.

It will be obvious that in case a reverse potential of energy is improperly applied to the operating winding W from an adjacent track section for example, the current will in this case flow from right to left through the winding W thereby forming a north pole at the outer end of core piece II and a south pole at the outer end of core piece I2. The poles of the electromagnet now tend to send flux through armature 24 in the same direction as the poles of the permanent magnet 8, and consequently the attraction of armature 24 is increased so that it still remains in its attracted position, whereby it is clear that the armature 24 can only be released by one polarity of energization of the winding W.

A relay has thus been provided wherein the armature is normally attracted upwardly by permanent magnet flux when the operating winding is deenergized and when energized the path of the permanent magnet flux is diverted into another circuit which does not include the armature, thereby releasing or causing the armature to be operated downwardly by gravity, or of course a spring biasing means could be provided. In comparing the magnetic structure of the present relay to that of a conventional tractive type relay, it will be obvious that the magnetic flux required to effect armature operation is not entirely created by energization of the electromagnet as is the case in the usual tractive relay, but rather the armature operating flux is maintained and diverted from the armature by energization of the electro-magnet. In this manner, the time ordinarily required for the armature operating flux to build up and for it to decay in a cycle of operation of the usual relay is greatly reduced by the present magnetic structure, which together with an electro-magnet is low self-inductance provided by the air gap in its magnetic circuit results in a magnetic structure capable of operating an armature in response to impulses of energy of a much higher frequency than the conventional relay magnetic structure.

In order to obtain the advantages of the above maginetic structure, a relatively light weight armature has been provided to cooperate therewith in order to maintain the inertia of the moving parts within a Value permitting efl-lcient contact operation at relatively high speeds. In other Words an improved glass enclosed armature and contact assembly has been provided to permit the use of a relatively light Weight armature and yet provide reliable contact operation thereby as the evacuation or inert gas surrounding the contacts prevents oxidation of the contacting surfaces to permit the required load to be controlled by these contacts at the reduced contacting pressure obtained from the reduced armature weight. An important feature of the present invention is the provision of a glass enclosed armature unit wherein the glass enclosure does not introduce an air gap in the armature operating magnetic circuit, or in other words the pole pieces l6 and I8 by extending through the glass enclosure provide a continuous low reluctance magnetic circuit connecting the operating structure with the armature thereby providing greater efliciency and sensitivity.

Another important feature of the present invention is the provision of a relay having an operating magnetic structure which operates an armature in response to one polarity of energization of its operating winding but which is inherently immune to the other polarity of energization, which feature is particularly valuable in coded track circuit systems as previously stated to prevent unauthorized operation of the relay from an adjacent track section having a reverse polarity of energy in the event of a failure of an insulating joint.

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The above rather specific description of one form of the present invention is given solely by way of example, and is not intended in any manner whatsoever in a limiting sense. It is also to be understood that various modifications, adaptations and alterations may be applied to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention, except as limited by the appended claims.

What I claim is:

1. In a relay, a permanent magnet, an electromagnet core coupled in multiple with the permanent magnet, an air gap in the electro-magnetic core, an armature normally attracted by the permanent magnet to a position completing a magnetic circuit in multiple with the electromagnet core, and a winding on the electro-magnet core operable to release the armature when energized with current of one polarity only.

2. In a relay, a permanent magnet, an electromagnet core coupled in multiple with the permanent magnet, means for varying the reluctance of the electro-magnet core, an armature normally attracted by the permanent magnet to a position completing a magnetic circuit in multiple with the electro-magnet core, and a winding on the electro-magnet core operable to release the armature when energized with current of one polarity only.

3. In a relay, a permanent magnet, an electromagnet core coupled in multiple with the permanent magnet, means for varying the reluctance of the electro-magnet core, an armature normally attracted by the permanent magnet, and a winding on the electro-magnet core operable to release the armature when energized with current of one polarity only.

4. In a relay, two spaced vertical magnetic members, a permanent magnet connected between the vertical members, an armature attracted to the lower ends of the vertical members by the permanent magnet, and an electro-magnet having an incomplete magnetic core connected between the vertical members whereby to release the armature from the vertical members upon one polarity of energization of the electro-magnet.

5. In a relay, two spaced vertical magnetic members, a permanent magnet connected between the vertical members, an armature attracted to the lower ends of the vertical members by the permanent magnet, an electro-magnet having an incomplete magnetic core connected between the vertical members whereby to release the armature from the vertical members upon one polarity of energization of the electro-magnet, contact means operated by the armature, and an evacuated enclosure for the armature and the contact means.

6. In a relay, a permanent magnet, an armature normally attracted by the permanent magnet, an electro-magnet for releasing the armature, contacts operated by the armature, and an evacuated enclosure for the armature and the contacts, wherein the flux from the permanent magnet is conducted into the enclosure through a continuous circuit of magnetic material.

'7. An enclosed relay operating machanism, comprising an armature and a contact assembly carried thereby, extending pole pieces carrying the armature and contact assembly, an open glass case with protruding metal rings molded therein and receiving the pole pieces with the armature and contact assembly positioned within the open glass case, a soldered joint connecting the metal rings to the pole pieces, a glass cover hermetically covering the glass case, the glass case being evacuated and hermetically sealed.

OSCAR S. FIELD. 

